In a high speed impact printer such as a wire matrix printer, for example, the spacing or gap between a platen and a printhead is very small and critical. For example, the spacing may be between 0.016 inches and 0.032 inches depending upon the thickness of the recording medium on which printing is to occur. A thicker recording medium such as an envelope, for example, would require a greater gap than a single sheet of paper.
When a printer is controlled by a personal computer (PC), a remote control signal from the PC is required to change the gap or spacing between the printhead and the platen when the thickness of the recording medium changes with respect to the prior recording medium on which printing has occurred. This is necessary to insure the desired print quality.
At the same time, it is desired for the printer to be capable of having the gap or spacing between the printhead and the platen to be manually adjusted by a user when the printer is not under control of the PC. This enables a user to have a plurality of selections as to the size of the gap or spacing.
Two previously suggested mechanisms for adjusting the gap or spacing between a printhead and a platen are disclosed in U.S. Pat. No. 4,268,177 to Veale and U.S. Pat. No. 4,657,415 to Kikuchi et al. The mechanism of the aforesaid Veale patent is capable of only manually adjusting the space or gap. While the mechanism of the aforesaid Kikuchi et al patent discloses a manual adjustment of the space or gap, it states that this motion also may be accomplished by activating a solenoid. However, the mechanisms of the aforesaid Veale and Kikuchi et al patents are not capable of having either manual or automatic adjustment of the gap as is required when seeking to remotely control the size of the gap while still enabling a user to manually control the gap size when desired.